OSB Roofing Wetness

wiz561

Hi!

I've have this re-occurring problem with my dryer venting through the roof. It seems like it's not terminated properly. When the outside roof vent is clogged with lint, it exhausts back into the attic.

Over time, this has caused the OSB around the vent to change a different color and get wet. Here are some pics of it...



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It is only in this one section of the joist. We ran the dryer last night and I just took the picture today. It's cold outside, so I don't expect the osb to dry out for awhile. The OSB is stamped Exposure 1, 1r24/2f16 (i think, the stamp is blurred), csa 0325, mill 002, 24/16.

How bad is this? I just bought a vent filter to install, and after the builder looks at it tomorrow, I plan on having it sealed up tight. I also plan on removing the bird screen that covers the vent because a lot of lint gets caught up in that (there's still a flapper).

Is there anything else I should do?

Thanks in advanced.

DexterII

Please forgive me if I am wrong (happens often any more), but don't you have a thread already running on this matter. Not being harsh, but I believe that you will obtain better results by confining the problem to a single thread.

joecaption

The picture in your last post showed the wrong type of pipe used to go through the roof. You used seamed pipe.
Far better to have gone through a side wall then the roof.
Has anyone gone up on the roof to look at the roof boot to see if the seal is shot?

jklingel

OSB does not like water. Fix this asap.

wiz561

Dexter: Yes, you are correct. I figured it was more of a general question about OSB than a specific dryer vent question, but yet they are related. I don't know, but can you 'merge' messages?

Joe: The sidewall is really far from the dryer. The dryer's in the middle of the house, so you're looking at about at least 30'. As far as the piping goes, I thought that you want to use the non-flex straight vent pipes. What should you use?

Jklingel: I plan on fixing this before using the dryer again. Should I expect anything bad from the OSB? Will it just rot away and fall off?

Thanks all for the responses. Sorry for starting a new thread about it, but I was more concerned about the dampness of the osb.

Thanks again

joecaption

How far is it from a soffit? Home Depot and Lowes sell a soffit vent system.

rusty baker

That's why I don't like OSB as roof sheathing.

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joecaption

And what would you suggest. Plywood would just delaminiate when it gets wet.

rusty baker

It will handle more water than OSB.

__________________
"I'm twisted, not sick. Sick implies, I'll get better"
Semi-Retired Installer
Installing since 1973

MJW

The argument is pointless. The moisture shouldn't be there in the first place. Plywood would be just as bad or worse.

Soffit is a bad idea for any exhaust vent.

Make sure you have the right vent on the roof and the pipe is fully insulated. Also make sure the pipe is directed out ASAP (no flex pipe that has any dips in it).

Not quite sure why it would get clogged so easy. Most lint is caught by the filter on the dryer.

Maybe the pipe needs to be replaced or completely cleaned out.

wiz561

Thanks all for the responses. I'm no expert, but I would think plywood would be worse off than OSB. I would think OSB is designed for water during construction because water does pool from rain and snow.

Venting out the soffit wouldn't be an option either. It's really hard to get up that high to change it, and I don't know how it would be venting longer horizontally than vertically.

As far as the water, I'm confused. The pipe is insulated in the cold attic area. The only thing that I can possibly think of is a separated pipe and the gap in the vent on the roof.

Last thing is that we also do use the lint trap in the dryer and my wife cleans it out all the time. It's a mystery why all this extra lint is getting out. Maybe something's goofy with the dryer.

jklingel

(1) OSB is PP w/ water in my experience, and Martin Holladay, on greenbuildingadvisor.com said, when this was being debated, that it "turns to oatmeal." I don't think that the durability of plywood vs OSB is even a contest. Read on the GBA forum and buildingscience.com. (2) Several things could be wrong at the roof, and all were mentioned, I think; dig into it and see. If there is no mold, you probably have no permanent, horrible deterioration. Probably. (3) Your dryer vent is notoriously sloppy about letting lint out. That is why at least one knowledgeable person on here suggests checking it in his signature. In my limited experience, the several I have owned all leaked lint.

ddawg16

Ignoring the OSB vs Plywood.....(each has advantages)

Your vent pipe needs to be a solid wall with a proper vent/backdraft preventer. That flexible stuff just gets clogged up with lint. But then again, your lint trap should be catching most of it. Hopefully your wife is not like my x who would wait until the vent screen had about 2" of lint on it. (one of many reasons why she is an x)

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jklingel

What? A guy trading a good woman for a clean dryer vent? My buddy just broke up w/ a gal because there was no skiing around where she lived, and she would not move. What is this world coming to?

wiz561

I'm sorry, but I think I missed where it said it in his sig. Could you please reference it?

Thanks!